Mourinho was completely successful with Chelsea, Inter Milan and Real Madrid. And he won titles with each club. Porto won the Champions League with Mourinho. Chelsea won 3 Premier League titles. Mourinho was successful with each club.
Whatever, Mourinho is not successful at the moment. Manchester United is not improving as expected. He was not even successful with Roma. Fenerbahce is not able to win the Super League title. I think Mourinho will probably take charge of a Saudi club after leaving the Super League.
To be fair he WAS good, doesn't mean he is still good. His style of football stayed back with how he was and then didn't really change. Look at Real Madrid, they won 5+ more UCL titles after he left, and many la liga titles, being good there is not an achievement.
Chelsea was Abrahimovic period, where they just poured money into the club, and even won the title more recently with Tuchel as well. The only achievement he had was with Porto, that was surreal and I agree that he was amazing there, and what he did was great, but no other team "over" achieved aside from that, they all did what was sort of expected of them. Sure still a great deal, because many expectations fail, so he did succeeded. But it has been a long time he did that again.